As we all know, steel and copper alloy welding will have a lot of problems, in the face of these problems, how to solve it? What about the welding process? Let’s take a look:
The main problem of welding is that cracks are easy to occur in the weld zone and fusion zone.
1) weld crack. The crack in the welding seam of steel, copper and its alloy is a thermal crack. The causes are as follows:
(1) copper and steel physical properties are very different, steel and copper thermal expansion and thermal conductivity is very different, so when the welding joint produced a great stress, resulting in weld crack.
(2) because copper and copper metal welding hot crack tendency is large and steel and copper and copper alloy welding when the weld is a mixture of iron and copper, so with the increase in copper content, the generation of hot crack tendency is also large.
2) seepage crack in heat affected zone. When steel is welded with copper and copper alloy, it is easy to produce seepage crack in steel in contact with liquid copper and copper alloy. Seepage crack is formed at high temperature.
Reason is: because of liquid copper and copper alloy steel osmosis and outcome of combined action of tensile stress, starting from the weld cooling moments, can produce tensile stress in the joint, the stress increases with continuous cooling and other organizations tend to have defects in the crystallization process of metal, produce micro cracks in the surface of the crystallization of steel, under the effect of welding tensile stress, the heat affected zone penetration cracks.
When the Ni content in the weld is more than 16%, no seepage cracks will occur on the low-carbon steel (NiCu alloy).
Ii. Welding process
Manual arc welding, argon arc welding, and gas shielded welding can be used to weld dissimilar joints of steel to copper and its alloys.
When welding copper and steel and their alloys, choose a filler metal, directly welding the two metals, in copper or steel surfacing welding transition layer, and then welding.
Due to the strong anti-permeability crack ability of the weld with nickel, the transition layer is deposited with pure nickel or nickel-based alloy containing copper. Nickel can greatly reduce or eliminate the infiltration effect of copper and copper alloy on steel, which is very helpful to eliminate the infiltration crack in the heat-affected zone, as shown in the figure:
Surfacing the transition layer and then welding.
1. Welding of purple steel and low carbon steel.
After surfacing and welding the transition layer, red copper can be used as filling metal material. In order to strengthen the deoxidation effect of the melting pool, si-mn bronze wire 201 and 202 are used for qsi3-1 welding. The welding quality and effect are better.
2. Silicon bronze and aluminum bronze are welded to low carbon steel.
After surfacing the transition layer, aluminum bronze can be used as the filling metal material qal9-2. At this time, the weld has a biphase structure, and the weld has a high thermal crack resistance. Also, the electrode copper 237 can be used as the filler wire to remove the coating and wipe it clean. Welding with ac argon arc welding.
3. Welding of brass and mild steel.
After surfacing the transition layer, in order to reduce the evaporation of brass and zinc, qsi3-1 silicon-manganese bronze wire is used as the filling metal, and qal9-2 aluminum-manganese bronze wire is also used as the filling metal material. If there is no round bronze wire, copper 237 electrode can be used to remove the coating, wipe it and conduct wire welding, and ac argon arc welding is used.
4. Iron copper and low carbon steel welding, welding low carbon steel after transition layer and iron copper (main ingredients Ni5 ~ 6.5%, Fe1.0 ~ 1.4%, and its mining for Cu), when welding the BFe5 ~ 1 can be used as the filler metal material, weld iron content is 32%, also have enough thermal cracking ability, welding, arc should deviate from the groove center, moved to the iron copper side, to guarantee the performance of the welded joint.
Because the nickel-copper alloy is similar to low carbon steel in its electrical and thermal conductivity, no preheating is required for welding.
There is also friction welding, although we are not very familiar with, but friction welding can get good welding joint.铜焊丝,Copper Welding Rods,铝焊丝,aluminium welding wire,镍焊条,Nickel electrode,药皮焊条,Flux Coated Brazing Welding Rods